This invention relates generally to gas turbine engine combustors and more particularly, to methods and apparatus for assembling gas turbine engine combustors.
Gas turbine engines include combustors which ignite fuel-air mixtures. At least some known combustors include annular dome assemblies which support a plurality of other combustor components. For example, dome assembly spectacle plates enable premixers to mate with downstream swirlers. Aligning the swirlers with respect to the premixers may be a complex task since the design tolerances of the premixers typically require more radial tolerance than circumferential tolerance. In addition, variations in the machined surfaces of the combustor components may further complicate the alignment process.
To facilitate aligning the swirlers with respect to the spectacle plate, at least some known swirlers include a locating pin that mates with a notch that is machined into the spectacle plate. More specifically, the locating pin and mating notch facilitate aligning or clocking the swirlers in such a manner to ensure radial movement of the premixers is permitted. In addition, the alignment of the swirlers directly influences the alignment of deflector plates that are coupled to the spectacle plate around the swirlers. More specifically, the locating pins facilitate the deflector plates being aligned with respect to the spectacle plate such that a pre-determined clearance is defined between adjacent deflector plates during the cold-assembled state.
The alignment of the deflector plates during the cold-assembled state directly affects the clearances between the deflectors at operating temperatures, and thus, may affect the useful life of the combustor. However, despite the use of the locating pins, variations in the machined features of the deflector plates and in the mating hardware, may still cause undesirable clearance variations between adjacent deflector plates. In addition, manufacturing the swirlers to include the pins increases the costs in comparison to those swirlers which do not include the locating pins. Furthermore, over time continued operation of a combustor with undesirable clearances may damage combustor components.